Plastic mulch debris in rhizosphere: Interactions with soil-microbe-plant systems

Large amounts of plastic mulch debris (PMD) accumulated in the soil can endanger agroecosystems. However, little is known about the interactions between PMD and soil-microbe-plant systems. In this study, a pot experiment (four replicates) in tropical greenhouse was conducted to investigate the effects of PMD (polyethylene) at different concentrations (0, 0.4, 0.8, 4.0, 6.0 g kg−1) on soil nutrients, rhizosphere bacterial communities and rice growth. This study further explored the interactive mechanisms between PMD and environmental factors based on correlation analysis and previous studies. The results showed that PMD continuously reduced the soil capabilities to store nutrients (C, N, P, humic-like substances) and increased the proportion of P and biodegradable dissolved organic matter (DOM). At the full ripening stage of rice growth, total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) in all PMD treatments significantly decreased by 60.86, 52.51 and 34.83% respectively as compared to CK (p PMD-microbe > PMD-plant, and the order of correlation between two environmental factors was soil-microbe > microbe-plant > soil-plant. Over all, PMD had the most significant negative effects on soil nutrients storage, followed by the change of microbial community structure and microbial metabolic functions. The negative effects of PMD on crops were relatively weak. [Display omitted] •The proportion of P was increased by plastic mulch debris (PMD) up to 110.34%.•PMD increased the total OTUs of bacteria by 0.03–17.05%.•PMD reduced the diversity and evenness of bacterial (Shannon) by 0.69–7.55%.•The rank of impact degree of PMD on factors were, “soil > microbe > plant”.•Specific influence mechanism of PMD on agroecosystem is indicated to be complex.